1. Field of the Invention
The present invention relates to a semiconductor device with high reliability and productivity, wherein a device can be easily mounted on a substrate in a flip-chip mounting, and to a method of manufacturing the device.
2. Description of the Background Art
Flip-chip-mounting of a device is usually performed in the following manner.
FIG. 10 is a schematic sectional view showing how a device is mounted to a substrate by the ordinary flip chip technique. Referring to FIG. 10, an individual semiconductor device 101 is prepared with bumps 104 on its surface. Bumps 104 of this semiconductor device 101 are aligned with electrodes 106a of a printed substrate 106. Thereafter, semiconductor device 101 is mounted on printed substrate 106, and bumps 104 and electrodes 106a are electrically connected by reflow-melting of solder. The solder may be bump 104 itself, or may be the solder precoated on printed substrate 106.
Then, a liquid material referred to as an underfill material 109 is injected between semiconductor device 101 and printed substrate 106 by injection equipment 130. This underfill material 109 is injected for the purpose of, for example, decreasing microstress on bumps 104, protecting semiconductor device 101 from external humidity or shocks, and ensuring sufficient reliability.
However, since underfill material 109 fills the space between semiconductor device 101 and printed substrate 106 employing capillarity, it has the following problems: filling requires a long time; air can be caught up, generating voids 131 inside, depending on the bump pattern; filling of a large chip is impossible; sufficient physical properties, such as heat resistance, are not ensured; and the total mounting processes are complicated.
One of the techniques to solve these problems involved in the underfill material is disclosed, for example, in Japanese Patent Laying-Open No. 11-307586.
FIG. 11 is a schematic sectional view showing a structure of a semiconductor device of the flip chip mounting type disclosed in Japanese Patent Laying-Open No. 11- 307586. Referring to FIG. 11, this laid-open application discloses a structure in which a thermosetting resin layer 205 and a protection film 206 are provided on the surface of a semiconductor device 201 where bumps 204 are formed. Here, the thermosetting resin layer 205 has such a nature that it is liquid at a temperature for connecting bumps 204 upon flip chip mounting of this semiconductor device 201, and is pushed away from the connecting section of the bumps 204 by pressure used for mounting and enables the bumps 204 and electrodes of the printed substrate to be joined together.
The thermosetting resin layer 205 is applied to the bumps-forming-surface of the semiconductor device 201 and dried thereafter, or applied by coating, or by flow of a melted film- or sheet-shaped thermosetting resin under pressure.
However, in the semiconductor device of the flip chip mounting type disclosed in the above-mentioned laid-open application, steps of previously applying (coating) liquid thermosetting resin and solidifying the resin by drying or other means after the application are needed. In addition, in the case of a film- or sheet-shaped thermosetting resin, coating had to be performed in a melted state by means of pressurized flow, for example.
In addition, after a dicing process, since an individual semiconductor device has that surface on which bumps are provided (a surface on which a semiconductor integrated circuit is formed) facing upward (and a dicing sheet is adhered on a lower surface), the individual semiconductor device had to be picked up carefully to avoid contact with the bumps on its upper surface.
An object of the present invention is to provide a semiconductor device which enables good flip chip bonding without any gaps between a device and a substrate by a simple manufacturing process, and a method of manufacturing the semiconductor device.
Semiconductor device of the present invention includes a flip chip device with bumps formed on its surface and a sheet provided on the bumps-formed surface of the flip chip device. The sheet has a base material layer and a flip-chip-side adhesion layer for adherence of the base material layer to the flip chip device, and its structure is such that, a part of the sheet melts by heating and tears by pressuring during flip chip bonding.
According to the semiconductor device of the present invention, since the sheet melts by heating and tears by pressuring during flip chip bonding, bumps are exposed from the torn sheet. Then the exposed bumps can be electrically connected to electrodes on a surface of a substrate.
Such sheet is adhered on the bumps-formed surface of the flip chip device by an adhesion layer. Therefore, in contrast to the conventional example, steps of applying liquid thermosetting resin and solidifying thereafter by drying, e. g., are unnecessary. It is also unnecessary to coat with film- or sheet-shaped membrane in melted state by pressure flow, for example. Thus, the manufacturing steps can be simplified compared to that of conventional example.
In addition, the sheet torn at flip chip bonding is embedded between the flip chip device and the substrate after flip chip bonding, so it can eliminate the gaps therebetween.
Furthermore, since the bumps are covered with the sheet by adhering of the sheet prior to dicing process, the semiconductor device can be picked up without contacting with the bumps after dicing. This prevents sticking of foreign matters on surfaces of bumps and establishes good connectivity between bumps and electrodes of the mounted substrate.
Furthermore, high positional accuracy or high load is unnecessary upon adhering the sheet to the flip chip device, because the employed sheet has such a structure that a part of the sheet melts by heating and tears by pressuring during flip chip bonding.
In the semiconductor device described above, it is preferable that a substrate having electrodes on its surface is further provided. The bumps are exposed from the sheet surface when the sheet is torn, and the exposed bumps are electrically connected to electrodes on a surface of the substrate by flip chip bonding.
Thus, good connection between the bumps and the electrodes is established, and flip chip bonding can be carried out by simpler steps as compared to conventional example.
In the semiconductor device described above, it is preferable that the flip chip device bonded to the substrate by flip chip technique is sealed with an insulator.
Thus, the present invention can be applied, for example, to CSP (Chip Scale Package) or BGA (Ball Grid Array).
In the semiconductor device described above, it is preferable that the sheet is embedded between the flip chip device and the substrate without gaps.
This can enhance adhesion of the flip chip device and the substrate.
In the semiconductor device described above, it is preferable that the sheet has a substrate-side adhesion layer provided on a surface opposite to that surface on which a flip-chip-side adhesion layer of a base material layer is provided.
This can increase junctional strength of the flip chip device to the substrate.
Manufacturing method of the semiconductor device according to the present invention includes the following steps.
First, the sheet having a base material layer and an adhesion layer is adhered on the bumps-formed surface of the flip chip device with the adhesion layer to cover the bumps. Then the flip chip device with the sheet adhered is flip-chip-bonded to the substrate having electrodes by pressuring and heating. A part of the sheet melts by heating and the sheet tears by pressuring during this flip chip bonding, and bumps are exposed from the torn sheet. Then the bumps and the electrodes are electrically connected to each other.
According to the manufacturing method of the semiconductor device of the present invention, the sheet is adhered on the bumps-formed surface of the flip chip device by an adhesion layer. Therefore, in contrast to the conventional example, steps of applying liquid thermosetting resin and solidifying thereafter by drying, e. g., are unnecessary. It is also unnecessary to coat with film- or sheet-shaped membrane in melted state by pressure flow, for example. Thus, the manufacturing steps can be simplified compared to that of conventional example.
In addition, the sheet torn at flip chip bonding is embedded between the flip chip device and the substrate after flip chip bonding, so it can eliminate the gaps therebetween.
Furthermore, since the bumps are covered with the sheet by adhering of the sheet prior to dicing process, the semiconductor device can be picked up without contacting with the bumps after dicing. This prevents sticking of foreign matters on surfaces of bumps and establishes good connectivity between bumps and electrodes of the mounted substrate.
Furthermore, high positional accuracy or high load is unnecessary upon adhering the sheet to the flip chip device, because the sheet has such a structure that a part of the sheet melts by heating and tears by pressuring during flip chip bonding.
In the manufacturing method of the semiconductor device described above, it is preferable that the sheet is adhered to the flip chip device in a vacuum chamber under atmosphere of increased degree of vacuum.
This allows the sheet to adhere without gaps to the surface of the flip chip device when the sheet tears. It is therefore possible to embed without any gaps between the flip chip device and the substrate after flip chip bonding.
In the manufacturing method of the semiconductor device described above, it is preferable that the step of forming the flip chip device by dicing a semiconductor wafer is further included, wherein the sheet is adhered to the semiconductor wafer prior to the dicing of the semiconductor wafer.
This can simplify the manufacturing steps, because adhering the sheet to every semiconductor chip after dicing is unnecessary.
In the manufacturing method of the semiconductor device described above, it is preferable that the sheet is prepared integrated into the dicing sheet.
This eliminates either the step of adhering the sheet to the semiconductor wafer or the step of adhering the semiconductor wafer to the dicing sheet, and can further simplify the manufacturing steps.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.